Why the Age Issue Is Hurting Biden So Much More Than Trump

“Even though we know both candidates are three and a half years apart, one side seems to have it sticking a little more, and that’s going to be a concern,” said Representative Mark Pocan, Democrat of Wisconsin.

Some of it comes down to basic physical differences.

Mr. Biden’s voice has grown softer and raspier, his hair thinner and whiter. He is tall and trim but moves more tentatively than he did as a candidate in 2019 and 2020, often holding his upper body stiff, adding to an impression of frailty. And he has had spills in the public eye: falling off a bicycle, tripping over a sandbag.

Mr. Trump, by contrast, does not appear to be suffering the effects of time in such visible ways. Mr. Trump often dyes his hair and appears unnaturally tan. He is heavyset and tall, and he uses his physicality to project strength in front of crowds. When he takes the stage at rallies, he basks in adulation for several minutes, dancing to an opening song, and then holds forth in speeches replete with macho rhetoric and bombast that typically last well over an hour, a display of stamina.

“It is the perception of how you communicate,” said Carol Kinsey Goman, a speaker and coach on leadership presence. “When Trump makes those kinds of faux pas, he just brushes it off, and people don’t say, ‘Oh, he’s aging.’ He makes at least as many mistakes as Joe Biden, but because he does it with this bravado, it doesn’t seem like senility. It seems like passion.”

With Mr. Biden, Ms. Goman said, “it looks like weakness.”

It is difficult to go beyond public perception to compare the physical health of the two men. Democrats and some Republicans have said Mr. Biden remains sharp in private conversations. Mr. Biden and Mr. Trump have each released limited medical information. Nearly a year ago, the White House released a letter from Mr. Biden’s longtime doctor describing him as a “healthy, vigorous 80-year-old male” after a physical examination. The White House has not made his doctors available to reporters. In November, Mr. Trump released a vague health report describing his condition as “excellent.”